Sifting apparatus

ABSTRACT

A sifting apparatus comprising screens arranged in polygonal formation within a rotary drum, the assembly of screens being resiliently suspended within the drum and subjected to vibration by a motor driving eccentric weights.

United States Patent Inventor Filed Patented Assignee Priority Guy Quesnel Gif, France 796,039

Feb. 3, 1969 July 6, 197 l Stein 8: Roubaix Paris, France Feb. 9, 1968 France SlFTlNG APPARATUS 3 Claims, 2 Drawing Figs.

US. Cl

Field of Search 209/405, 209/407 Int. Cl 1. B07b 1/26 References Cited UNITED STATES PATENTS 11 1914 Teg 9 1942 Henry .1 9 1953 Ahlfors.... 2/1955 Dekanski FOREIGN PATENTS 2/1926 Germany Primary Examiner-Frank W. Lufter Assistant Examiner-William Cuchlinski, Jr. At!orneyWaters, Roditi, Schwartz & Nissen ABSTRACT: A sifting apparatus comprising screens arranged in polygonal formation within a rotary drum, the assembly of screens being resiliently suspendedwithin the drum and subjected to vibration by a motor driving eccentric weights.

PATENTED JUL 6 l9?! SIFTING APPARATUS FIELD OF THE INVENTION The present invention relates to sifting apparatus, such as sieves, for separating particulate materials in dependence upon their sizes by passing them through screens.

BACKGROUND OF THE INVENTION The sieves at present used are either cylindrical or conical structures pierced with suitable openings and driven in rotation, or flat sieves subjected to pulses and vibrations.

The first type of apparatus, that exerts a crumbling action by repeated reversal of the mass has the disadvantage of involving clogging of the openings, such that the efficiency is low. The second type of apparatus, in which the vibration of the mass causes stratification favourable to sifting, has however the disadvantage of being very cumbrous.

A sieve according to the invention comprises a cylindrical drum capable of being driven in rotation and in which is suspended a frame which is solid with means capable of cansing it to vibrate and which supports sifting means disposed along the faces of a prism coaxial with the drum, means permitting feeding of products to be sifted into the interior of the frame, and means effecting the evacuation of the retained material and of the fine particles.

Preferably the frame is suspended in the drum by springs, in such manner that the vibrations of the frame are not communicated to the drum.

With a suitable driving speed of the drum the unit is set in rotation and, moreover, the sifting plates vibrate. The product slides, continuously cascading lightly on to the plate owing to the vibrations. The clogging effects are greatly reduced and, moreover, the space occupied by the apparatus is reduced.

Other details, also forming a part of the invention, will appear in the course of the following description with reference to the accompanying drawing in which:

FIG. I is a diagrammatic view in axial section ofa sifting apparatus according to the invention, and

FIG. 2 is a cross section on the line II/II in FIG. 1.

The sieve illustrated in the drawing comprises a cylindrical drum 1 capable of being driven in rotation. For this purpose the drum preferably rests on four pneumatic tires or trains of pneumatic tires 2 which both support and drive the said drum. The driving in rotation may be effected through the intermediary of speed reduction gearing 3 driven by a motor 4. The pneumatic tires are supported by a chassis 5. Means prevent any longitudinal movement of the drum. For example, there may be provided a steelplate 6 welded at right angles to the drum and extending between two horizontal friction rollers 7 likewise fixed to the chassis 5.

In the interior of the drum is suspended, through the intermediary of springs 8, a movable frame 9 which supports sifting plates or screens 10 disposed along the faces of a prism coaxial with the drum. The ends of the plate comprise hooks such as 10a cooperating with hooks ll of the frame, one of the hooks being capable of being shifted by virtue of a bolt system lla. In this manner the plates are kept straight.

The movable frame 9 is made solid, by means ofcrosspieces such as 9a and a generally Y-shaped end support structure 9b, with a motor 12 with eccentric flyweights which is intended to cause the frame 9 to vibrate in the interior of the drum 1, this latter being prevented from vibrating owing to the suspension by springs 8.

The sieve according to the invention may be used horizontally, in which case an advancing movement may be imparted to the material on the sifting plate by unbalancing one of the flyweights 13 relative to the other one 14. The apparatus may equally well be inclined in such manner as to impart a natural advancing movement 0 the material.

Of course, the sieve is completed by a feeding channel 15 bringing the product to be sifted into a drum 15a communicating with the interior of the prism defined by the frame 9 and the sifting plates. The retained products are evacuated via a channel 16 fed by the outlet drum 16a, whilst the fine products which have passed through the plate 10 fall into the interior of the drum 1 and are collected at the outlet in a channel 17.

The speed of rotation of the sieve is selected so that the product slides on the plate 10 whilst cascading slightly.

One of the advantages of such a sifting apparatus according to the invention is that it permits passage beneath the product of a plate which is continuously suitable. Indeed, the particles which have difficulty in passing through the plate and which if they did not would clog it have a tendency to detach themselves when the said plate, subjected to vibrations, reaches the vicinity of the highest point of its path.

The sieve according to the invention also has the advantage of relatively small size. Indeed, instead of the flat surface of conventional apparatus there is in fact a surface enveloping a curve that passes beneath it. Assuming, for example, that a particle goes from the point 18 to the point 19(FIG. 1) during the time corresponding to one rotation ofthe drum, the length of the sieve across which it will be obliged to pass is equal to the diameter of the sieve multiplied by 7r.

Of course, the practical form described has been given mainly by way of example, and it may undergo numerous modifications without thereby exceeding the scope of the present invention.

Iclaim:

I. l. A sifting apparatus for separating particulate materials, comprising;

a cylindrical drum;

a plurality of pneumatic tires adapted to rotatably mount said cylindrical drum;

drive means connected to at least one of said tires so as to rotate said tire and correspondingly impart rotation to said cylindrical drum;

frame means positioned within said cylindrical drum;

spring means connected to said cylindrical drum and to said frame means so as to resiliently suspend said frame means within said drum;

screens supported on said frame means for rotation therewith, said screens being arranged forming the surfaces of a prism generally coaxial with said drum; vibration generating means fastened to said frame means and adapted to impart vibratory movement thereto; means for feeding particulate materials to be sifted to the interior of said prism; and,

means for removing sifted particulate materials from said drum and prism.

2. A sifting apparatus as claimed in claim 1, wherein said vibration generating means comprises a motor including eccentric weight means connected to said motor, said motor being adapted to drive said eccentric weight means so as to vibrate said frame means 3. A sifting apparatus as claimed in claim 1, wherein said drum is rotatable about a generally horizontal axis, and said eccentric weight means comprise unbalanced weights so as to generate vibrations deflecting said frame means relative to said axis, thereby advancing the particulate materials to be sifted along the length of said prism. 

1.
 1. A sifting apparatus for separating particulate materials, comprising; a cylindrical drum; a plurality of pneumatic tires adapted to rotatably mount said cylindrical drum; drive means connected to at least one of said tires so as to rotate said tire and correspondingly impart rotation to said cylindrical drum; frame means positioned within said cylindrical drum; spring means connected to said cylindrical drum and to said frame means so as to resiliently suspend said frame means within said drum; screens supported on said frame means for rotation therewith, said screens being arranged forming the surfaces of a prism generally coaxial with said drum; vibration generating means fastened to said frame means and adapted to impart vibratory movement thereto; means for feeding particulate materials to be sifted to the interior of said prism; and, means for removing sifted particulate materials from said drum and prism.
 2. A sifting apparatus as claimed in claim 1, wherein said vibration generating means comprises a motor including eccentric weight means connected to said motor, said motor being adapted to drive said eccentric weight means so as to vibrate said frame means
 3. A sifting apparatus as claimed in claim 1, wherein said drum is rotatable about a generally horizontal axis, and said eccentric weight means comprise unbalanced weights so as to generate vibrations deflecting said frame means relative to said axis, thereby advancing the particulate materials to be sifted along the length of said prism. 